ASO

Question 1

In acute streptococcal infection, the toxic immunogenic exoenzyme _____ is produced in response to Streptolysin O antigens.

Answer 1

Anti Streptolysin O (ASO)

Question 2

pH of ASO latex

Answer 2

8.2

Question 3

Composition of the ASO Latex Kit

Answer 3

• ASO latex
• Positive control
• Negative control
• Reusable test cards
• Pipettes/stirrers

Question 4

The positive control consists of:

Answer 4

• Human serum with ASO >200 IU/mL
• Preservative

Question 5

The negative serum consists of:

Answer 5

• Animal serum
• Preservative

Question 6

Sample/specimen used in ASO Latex Agglutination Test

Answer 6

Serum

Question 7

Composition of the ASO Latex reagent?

Answer 7

• Suspension of white latex particles coated with Streptolysin O (pH 8.2)
• Preservative

Question 8

Considering that the reagent contains <0.1% sodium azide, what precautions should be observed?

Answer 8

• It may be toxic if ingested
• It may react with lead and copper plumbing to form explosive metal azides

Question 9

Storage temperature of the latex and controls

Answer 9

2-8 °C

Question 10

Storage position of latex and control vials

Answer 10

Vertical

Question 11

Ideal storage conditions of the serum to be used for testing

Answer 11

Serum stable for 48 hours at 2-8 °C

Question 12

Storage condition of the sera if longer storage conditions are necessary

Answer 12

Frozen at -20 °C

Question 13

Samples should be free from these factors:

Answer 13

• Contamination
• Hemolysis
• Lipemia

Question 14

Materials that are required but not supplied by the kit:

Answer 14

• Mechanical rotator (set at 100rpm)
• Vortex mixer
• 9 g/L saline solution

Question 15

Which groups of hemolytic Streptococci liberate Streptolysin O antigens?

Answer 15

A, C, and G

Question 16

Measurement of ____ is important in the investigation of post-streptococcal diseases.

Answer 16

ASO Antibody titre

Question 17

At what temperature should the samples and reagents be during testing?

Answer 17

room temperature

Question 18

Volume of sample to be used during testing

Answer 18

50 µL

Question 19

Amount of control to be used during testing

Answer 19

1 drop

Question 20

Amount of latex reagent to be used in testing

Answer 20

1 drop

Question 21

In qualitative testing, the test should be read after ____

Answer 21

2 minutes

Question 22

In qualitative testing, what could occur if the test is read longer than 2 minutes?

Answer 22

False positive

Question 23

In qualitative testing, what equipment can be used in rotating the cards?

Answer 23

Mechanical rotator set at 100 rpm

Question 24

In qualitative testing, what should be observed after rotating the cards?

Answer 24

Agglutination

Question 25

In what ways can the ASO-latex reagent be mixed before using?

Answer 25

• Manually
• Vortex mixer

Question 26

In the semi-quantitative test procedure, this solution is added first

Answer 26

50 µl of 9 g/L saline

Question 27

Volume of ASO in a neat dilution

Answer 27

200 IU/mL

Question 28

Volume of ASO in a 1:2 dilution

Answer 28

400 IU/mL

Question 29

Volume of ASO in a 1:4 dilution

Answer 29

800 IU/mL

Question 30

Volume of ASO in a 1:8 dilution

Answer 30

1600 IU/mL

Question 31

What does the presence of a visible agglutination indicate?

Answer 31

Content of Anti-streptolysin ≥200 IU/mL

Question 32

What test is done to a positive sera?

Answer 32

Titred by making serial two-fold dilutions in 9g/L saline